JPS63248492A - Method of extracting cation and application thereof to aqueous effluent - Google Patents

Abstract

A process for the extraction of cations from an aqueous effluent. An effective quantity of at least one polymer or copolymer, which is physically or chemically crosslinked, is introduced into the aqueous effluent. The polymer or copolymer is based on one or more units selected from salified acrylic acid, quarternized acrylic acid, and a copolymer comprising from 40 to 60 mole % of acrylic acid and from 60 to 40 mole % of at least one dialkylaminoalkyl acrylate in which each alkyl group contains from 1 to 4 carbon atoms. This process is used to treat aqueous effluents.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to the field of treatment of aqueous effluents containing cations.

BACKGROUND OF THE INVENTION Methods for extracting metals from aqueous effluents using ion exchange resins are already known. For example, French Patent No. 2.068.158 discloses that strontium-90 is extracted by making radioactive waste completely alkaline, at least to a pH of 10, and passing it through a carboxylic acid resin, which is a cation exchanger. It is stated that. Furthermore, it is known from US Pat. No. 4,156,658 to fix radioactive ions such as strontium-90 and cesium-137 in soil. According to this method, soil containing radioactive ions is injected with a chemical composition containing sodium acrylate, acrylamide, and N,N-methylene-bisacrylamide that can polymerize to form a gelled structure; Next, initiators and catalysts are injected into the soil to cause polymerization and formation of an ion-exchange gel within the soil.As a result, the gelled structure physically binds the soil and ions, and the ions in the gel The exchange properties chemically fix ions. Further, U.S. Pat. No. 4,235,737 teaches that radioactive particles at pH 5.
．． It is known to treat aqueous or organic liquids larger than 5. In this method, an effective amount of an absorbent consisting of an alkali metal salt of polyacrylonitrile grafted onto starch is added to the liquid. The radioactive element of particular interest in this method is iodine, and the amount of polymer used in this process is preferably from 1 to 2000 times the weight of the radioactive liquid.

Further, U.S. Pat. No. 3,995,009 describes an ion exchange method in which a cation exchange resin of the ammonium type, such as a divinylbenzene acrylate copolymer with carboxylic acid functionality, is contacted with an aqueous solution of uranyl fluoride. ing.

U.S. Pat. No. 3,216,7860 includes p.
A method is described for recovering heavy metals from a solution containing a compound in which H is 4 or more and the metal is present in the form of a cation. The method consists of the following steps: (a) Contacting the above solution with a slightly acidic ion exchange resin. This resin includes a crosslinked matrix to which carboxylic acids are bound. This matrix is made by copolymerizing 0.5 to 50% by weight of an unsaturated polyethylene monomer (crosslinking agent) and 50 to 99.5% by weight of an unsaturated monoethylene monomer (e.g., acrylic acid or methacrylic acid) in an organic solvent. It is obtained by removing occluded organic solvent from a crosslinked copolymer to obtain a sponge-like structure.

(c) Washing the ion exchange resin using acid to remove absorbed heavy metal ions and regenerating the ions.

Furthermore, French Patent No. 2.553.678 states:
Polymers of N-alkyl- or N-alkoylene-substituted acrylamides or methacrylamides and copolymers of the above-mentioned (meth)acrylamides containing less than 30% by weight of at least one ionic comonomer, in particular acrylic acid, methacrylic acid and their salts. It describes about. These (co)polymers are made, for example, by polymerization in reverse phase suspension and have a water absorption capacity that varies depending on temperature. Therefore, when heated, these (co)polymers contract, even in the presence of a considerable excess of water, releasing the water once absorbed. This water absorption capacity is hardly affected by the presence of inorganic salts in the water. Even if the aqueous solution contains a low molecular weight solute, such as an inorganic salt, the copolymer absorbs the aqueous solution containing the solute.

Thus, in the prior art, acrylic polymers have been used to treat wastewater, especially containing radioactive ions, in the form of ion exchange resins or in special conditions of underground extraction.

In the case of U.S. Pat. No. 4,235,737, the weight of the polymer used is always greater than the amount of liquid treated, so the high cost of the polymer makes this process particularly difficult for high-value effluents. It should be noted that only applicable

As used herein, an "ion exchange resin" is a solid, non-swelling compound that retains its physical structure during the performance of an ion exchange process. In contrast, acrylic polymers with water absorption ability change from a powder state to a gel state, in other words, their physical structure changes.

Problems to be Solved by the Invention The problems to be solved by the present invention are to provide an effective and effective solution regardless of the cation concentration in the effluent without using expensive and ineffective ion exchange resins. The objective is to economically extract cations from an aqueous effluent containing cations.

Here, "economical" extraction means that the method of the present invention uses a small amount of the aqueous effluent to be treated; therefore, the method of the present invention does not remove undesirable cations from the effluent. This means that it can be used in various fields, such as adjusting the useful cation content in the effluent.

Means for Solving the Problems A first object of the invention is to use at least partially chlorinated and/or quaternized acrylic acid in a process for extracting cations from an aqueous effluent containing cations. Adding to the effluent an effective amount of at least one physically or chemically crosslinked polymer or copolymer based on 40 to 60 mol % of acrylic acid, optionally further at least partially chlorinated. and the alkyl group each have 1 to 4 carbon atoms and are optionally at least chlorinated or quaternized.
dialkylaminoalkyl acrylate 60-4
0 mol % of a copolymer is added to the effluent.

"At least partially chlorinated and/or quaternized acrylic acid" means acrylic acid partially substituted by at least one of its ammonium, alkali metal or alkaline earth metal salts. It means there is. "Dialkylaminoalkyl acrylate, partially chlorinated or quaternized if necessary"
means that the dialkylaminoalkyl acrylate partially contains at least one of its salts, such as its quaternary ammonium salt.
means that it has been replaced by one.

Preferably, the polymers used within the scope of the present invention are based on about 50 mole % or more of alkali metal acrylate, alkaline earth metal acrylate or ammonium acrylate and about 50 mole % or less of acrylic acid.

If the polymers or copolymers used within the scope of the invention are not naturally physically crosslinked by selecting a suitable production method, the polymers or copolymers of the invention are furthermore provided with an effective amount of at least one chemical crosslinker. You can put medicine in it. The amount of crosslinking agent, depending on the manufacturing method suitable for the polymer, may be up to about 5% by weight, preferably 0.5% by weight, based on the total amount of monomer components. (14 to 3% by weight).

As crosslinking agents that can be used within the scope of the invention, mention may be made, for example, of the following: (1) compounds having at least two polymerizable double bonds, and (2) at least one polymerizable double bond. A compound having a heavy bond and at least one functional group that reacts with at least one monomer constituting the polymer.

(3) A compound having at least two functional groups that react with at least one of the monomers constituting the polymer.

As compounds having at least two polymerizable double bonds as indicated in the first part above, the following may be mentioned: a) in particular divinylbenzene, divinyltoluene, divinylxylene, divinyl ether, divinyl ketone,
and divinyl compounds or polyvinyl compounds such as trivinylbenzene.

b) Polyols such as esters of polyols (ethylene glycol, trimethylolpropane, glycerol, polyoxyethylene glycol, polyoxypropylene glycol, etc.) and di(meth)acrylic acid or esters of tri(meth)acrylic acid, etc. Reaction of diesters or polyesters of saturated mono- or polycarboxylic acids, unsaturated polyesters (obtained by reacting unsaturated acids such as maleic acid with any one of the polyols mentioned above), and polyepoxides with (meth)acrylic acid. Di(meth)acrylic acid ester or tri(
meth)acrylic acid ester.

C) Bis(meth) such as N,N-methylene-bis-acrylamide and glyoxal-bis-acrylamide
Acrylamide.

d) Polyisocyanate (toluene diisocyanate,
hexamethylene diisocyanate), 4,4-diphenylmethane diisocyanate, and NG obtained by reacting the above diisocyanate with a compound containing an active hydrogen atom.
A carbamyl ester obtained by reacting a prepolymer (such as a prepolymer having an O group) with a monomer having a hydroxy group. Such unacarhamyl esters are, in particular, carbamyl esters of di(meth)acrylic acid obtained by reacting the above-mentioned diisocyanates with hydroxyethyl(meth)acrylate.

e) Di- or poly(meth)allyl ethers of polyols such as alkylene glycols, glycerol, polyalkylene glycols, polyoxyalkylene polyols, and carbon hydroxides, such as polyethylene glycol diallyl ether, allyl starch, allyl cellulose, etc.

f) Di- or polyallyl esters of polycarboxylic acids such as diallyl phthalate and diallyl adipate.

g) Esters of unsaturated mono- or polycarboxylic acids and mono-(meth)allyl ethers of polyols, such as esters of (meth)acrylic acid and monoallyl ethers of polyethylene glycol.

at least one monomer reacting with at least one polymerizable double bond as indicated in No. 2 above;
Compounds having two functional groups are ethylenically unsaturated compounds having at least one group that reacts with a carboxyl, anhydride, hydroxyl, amine or amide group. Examples of this compound include N-methylol (meth)acrylamide, glycidyl (meth)acrylate, and the like.

Compounds of the above third type having at least two functional groups that react with at least one of the monomers constituting the polymer are shown below. For example, (poly)ethylene glycol diglycidyl ether, (poly)propylene glycol diglycidyl ether and water-soluble compounds derived from diglycidyl ethers such as (poly)glycerol diglycidyl ether.

- haloepoxidized compounds, such as, for example, epichlorohydrin and methylepichlorohydrin.

- incyanate compounds, especially hexamethylene diisocyanate.

Polymers and copolymers that can be used according to the invention include:
They are obtained by polymerization in the presence of at least one radical initiator, whether in aqueous solution, in an inverse emulsion or in suspension in the presence of at least one emulsifier. This polymerization technique is well known to those skilled in the art. Various means are used to generate free radicals, in particular microwaves, β-rays, r-rays, ultraviolet radiation, or chemical initiators. If a chemical initiator is used, the polymerization initiator is selected, in particular, among persulfates, peroxides, hydroperoxides and diazo compounds.

When persulfates are selected as initiators, polyhydrophenonope sodium sulfite, sodium bisulfite, dimethylaminopropionitrile, diazomercaptan,
It can be used in combination with a reducing agent selected from ferrocyanide and iron sulfate. The initiator and, if necessary, the reducing agent are each used in a proportion of about 0.05 to 2% by weight, based on the total amount of monomers making up the polymer.

The polymer or copolymer obtained by this method is preferably in the form of particles with an average size of 1 to 1000 μm.

Examples of methods for making polymers or copolymers (with or without chemical crosslinking) that can be used in the present invention include, inter alia, U.S. Pat. No. 3,926,891;
No. 4.351.922, No. 4.062.817, No. 4.093.776, No. 4.507.438, European Patent No. 188.963, United States Patent No. 4.541.871 and European patent application 87/4
No. 01.825/2. Accordingly, their contents are incorporated herein.

It should be noted that the polymers or copolymers that can be used in the present invention are effective in extracting cations from aqueous effluents even in very small amounts. Preferably, the polymer or copolymer is used in an amount of about 0.02 to 20 g per aqueous effluent 11. In the present invention, "aqueous effluent" means a two-phase mixture comprising an aqueous solution and an aqueous phase.

The cations extracted by the method of the invention are extremely diverse. In particular, protons, deuterons, tritium ions, ammonium ions, quaternary ammonium ions, IA of the periodic table.

mA, IVA, VA, VIII, IB, IIBSVB metals and lanthanide, actinide cations. Examples of such metal cations include the monovalent cations of sodium, potassium, cesium, and silver, magnesium, calcium, strontium, barium,
divalent cations of radium, iron, cobalt, zinc, copper, nickel, cadmium, lead and mercury; trivalent cations of europium, bismuth and lanthanum; tetravalent cations of vanadium, cerium and thorium; and 6-valent cations of uranium. cations. In aqueous effluents where these cations are present, the cations extracted are halides, nitrates, sulfates, oxalates, carbonates, among others.
It is attached to various anions such as bicarbonate, acetate, or complexing ligands.

p of the aqueous effluent used in the cation extraction method of the present invention.
l( is preferably in the range of approximately 2 to 5.

The pH of the aqueous effluent after extraction is the initial pH of this aqueous effluent.
Please note that it can be as high as less than 3 units.

The extraction method according to the invention is carried out in one or more stages. When the process is carried out in multiple stages, the portion of the aqueous effluent not absorbed by the polymer is separated from the swollen polymer, transferred to a container, and again an effective amount of fresh polymer is introduced and the process continues. By repeating this operation as many times as necessary, the invention makes it possible to remove almost all undesired cations from the aqueous effluent, or even to adjust the content of useful cations in the effluent.

Therefore, a second object of the invention is the treatment of spring water, the desalination of water, the removal of contaminants from aqueous effluents containing radioactive waste (such as those discharged from nuclear power plants), the treatment of used water. ,
Alternatively, the method may be applied to the treatment of aqueous effluents, such as the treatment of industrial water effluents containing dissolved metal residues (such as catalyst residues originating from olefin polymerization units).

For the treatment of aqueous effluents containing radioactive waste, the advantage of the present invention is that the radioactive metal is concentrated in a small volume and in a form (swollen polymer) suitable for packaging using concrete.

In some cases, especially when the metal cation is a cation of a precious metal such as gold, silver, or platinum, or a cation of a rare metal such as vanadium, iridium, or uranium, the metal trapped in the gel may be recovered, especially by burning the gel. be done.

The method of treating aqueous effluents according to the invention by contacting them with polymers or copolymers as described above has the great advantage of being effective even when the cation concentration of the aqueous effluents is very low. Therefore, the concentration of cations in the effluent is 10
Even when the amount is less than ppm, up to 80% of cations can be removed. The processing method according to the invention is also carried out at temperatures ranging from about 5 to 80°C.

Example The invention will become clearer from the following examples.

However, these Examples do not limit the present invention in any way.

Examples 1 to 3 At a temperature of 18° C., a weight mi (expressed in g) of a polymer containing a metal cation M″″ (n is the valency of the metal M) was added to a concentration C1 (ppm) at a temperature of 18°C for about 15 minutes. Stir with 50 ml of an aqueous solution of chloride (as indicated). The polymer used is a physically crosslinked copolymer containing 80 mol % of a derivative of sodium acrylate and 20 mol % of a derivative of acrylic acid.

The polymer partially immobilizes the metal ions and expands.

The swelling of the polymer is determined by weighing the gel after filtration (final weight m, expressed in g).

At this time, the concentration of metal cations in the supernatant solution is measured by atomic absorption or emission spectrometry depending on the element. Therefore, the proportion of cations fixed in the gel (expressed in %) can be calculated. The results are shown in Table 1 below.

Examples 4 to 8 The same procedure as in Examples 1 to 3 is carried out, except that the aqueous solution extracted is a nitrate solution. The results are shown in Table 1 below.

Example 9 Concentration C1 (containing cation MI'l+ at a temperature of 20°C
(expressed in ppm) of the nutrient solution, weight mi = 1 g
Introducing the polymer of The polymer used is Aqua Keep (AQU) from NOR3OLOR.
This product is commercially available under the trade name AKEEP) X5. The whole is stirred for 2 hours. Next, it is filtered through a wire mesh with a porosity of 100 mesh. The polymer partially fixes the ions and is expanded. The expansion of the polymer is
Determined by weighing the gel after filtration (final weight m,
is expressed in g). The cation concentration in the eluate was determined by flame spectrophotometry (Mg and K) and the Nessler method (N
H4). Therefore, the proportion of cations fixed in the gel (expressed in %) can be calculated. The results are shown in Table 1 below.

Table 1 Example 10 A blue vanadyl sulfate pentahydrate voso,.5H20 aqueous solution is placed in a beaker at a temperature of 20°C. for a few minutes,
Add a small amount of the same polymer used in Example 9 while stirring. The solution is gradually decolorized and the polymer is observed to swell in the form of a blue gel.

Example 11 At a temperature of 20° C., a yellow aqueous solution of uranyl nitrate hexahydrate [02(NO3)2.6H20 is placed in a beaker.

Add the same polymer as in Example 10 while stirring for a few minutes. The solution is gradually decolorized and the polymer is observed to swell in the form of a yellow gel.

Examples 12 to 19 50 ml of a liquid solution containing 10 ppm of the metal in the form of the cation M"' (pH adjusted to 4 by adding nitric acid) is brought into contact with 2 mg of dry copolymer. The copolymer used is It contains X mol% of derivatives, (100-x) mol% of derivatives of acrylic acid, and 7% by weight of diethylene glycol diacrylate based on the total of acrylic acid and sodium acrylate.

Contacting is carried out for 30 minutes at a temperature of 25°C. after that,
Filter the solution and measure.

The metal retention of the gel (expressed in % and shown in Table 2 below) is calculated by the following formula: % = (Co V
o Ct V r ) / C, V.

In the above formula, Co and V. are the initial metal concentration and volume of the aqueous solution, and Cf and V are the metal concentration and volume of the aqueous solution not included in the gel after contact.

The results obtained for various metals by varying X and y, the neutralization rate of the acrylic acid of the copolymer and the crosslinking rate of the copolymer, are shown in Table 2 below.

Claims (1)

Scope of Claims: (1) A method for extracting cations from an aqueous effluent containing at least partially chlorinated and/or
or introducing into the aqueous effluent an effective amount of at least one physically or chemically crosslinked polymer or copolymer based on quaternized acrylic acid;
40 to 60 mol % of acrylic acid, optionally at least partially chlorinated, and the alkyl groups each having 1 to 4 carbon atoms, optionally at least partially salinated or quaternary. 60 to 40 mol % of at least one dialkylaminoalkyl acrylate, wherein the copolymer is a copolymer containing from 60 to 40 mol % of at least one dialkylaminoalkyl acrylate. (3) The cations extracted above are protons, deuterons, tritium ions, ammonium ions, quaternary ammonium ions, IA, IIA, and IV of the periodic table.
The cation extraction method according to claim 1 or 2, characterized in that the cation is selected from metals of groups A, VA, VIII, IB, IIB, and VB, and cations of lanthanides and actinides. . (4) The pH of the aqueous effluent to be extracted is from 2 to 5.
The cation extraction method according to any one of claims 1 to 3, wherein the cation extraction method is within the range of . (5) Cationic extraction according to any one of claims 1 to 4, characterized in that said polymer or copolymer is used in the form of particles with an average size of 1 to 1000 μm. Method. (6) Any one of claims 1 to 5, characterized in that the polymer used above has 50 mol% or less of acrylic acid and 50 mol% or more of alkali acrylate as main components. The cation extraction method described in Section. (7) The polymer or copolymer used above further comprises an effective amount of at least one chemical crosslinking agent according to any one of claims 1 to 6. cation extraction method. (8) The cation extraction method according to claim 7, wherein the amount of the chemical crosslinking agent is less than 5% by weight of the total amount of monomers constituting the polymer. (9) The concentration of cations in the above effluent is 10 ppm
A method according to claims 1 to 8, characterized in that: (10) The cationic extraction method according to any one of claims 1 to 9, wherein the extraction is carried out at a temperature of 5 to 80°C. (11) In a method for extracting cations from an aqueous effluent containing cations, a physically or chemically crosslinked acrylic acid based on at least partially chlorinated and/or quaternized acrylic acid; An effective amount of at least one polymer or copolymer is introduced into the aqueous effluent, optionally additionally 40 to 60 mole % of at least partially chlorinated acrylic acid and an alkyl group containing 1 to 4 carbon atoms each. at least one dialkylaminoalkyl acrylate, optionally at least partially chlorinated or quaternized, having 60 to 40
A method for treating an aqueous effluent comprising a cationic extraction step of introducing into the effluent a copolymer comprising mol %. (12) The treatment method according to claim 11, wherein the treatment is decontamination of effluent containing radioactive waste. (13) A treatment method according to claim 12, characterized in that, after said treatment, the expanded polymer obtained at the end of said cation extraction step is wrapped in concrete. (14) After the treatment, the expanded polymer obtained at the end of the cation extraction step is burned to recover the cationic metal.